Editorial: Plant-fungal interactions

COPYRIGHT © 2023 Dai, Suwannarach, Bamunuarachchige and Karunarathna. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Editorial: Plant-fungal interactions

Fungi are known to be older than plants, while plant-fungal interactions are as old as the evolutionary period of higher plants (Zeilinger et al., 2016). Some fungi interact positively or negatively with plant roots in the rhizosphere or aboveground parts of the plant (Barea et al., 2005). These fungi have different lifestyles viz., saprophytic, pathogenic, endophytic, or symbiotic, but the differences among different lifestyles are not always apparent (Błaszczyk et al., 2021). The beneficial plant-associated fungi assist their hosts by stimulating their growth, producing secondary metabolites, and improving their resistance to biotic and abiotic stresses (Verma et al., 2022). In contrast, pathogenic fungi cause diseases and are one of the major threats to crop yield and food security (Xu, 2022).
The fungi-plant interactions ranging from harmful to valuable associations, play a leading role in natural and agricultural ecosystems (Balestrini, 2021). These interactions affect agriculture, the environment, and ultimately the economy. Many fungi are yet to be discovered; thus, studying plant-fungal interactions is very important for finding these missing fungi and helpful for exploring their roles in the ecosystem (Antonelli et al., 2020). Studies should be conducted predominantly in the tropics since these regions have a high plant diversity that positively correlates with fungal diversity (Shen et al., 2021). Nevertheless, previous studies showed that even temperate plant species harbor many cryptic species. Hence, exploring the inhabiting fungi from the perspective of plant-fungal interactions in temperate and tropical regions is essential.
To create and spread a better understanding of this exciting area of research, we proposed the Research Topic "Plant-fungal interactions." In this Research Topic, we accepted 25 articles, including 23 original articles and two reviews on different aspects of plant-fungi interactions. An overview of the scientific content is summarized below. Lu et al. presented original research on how arbuscular mycorrhizae influence raspberry growth and soil fertility under conventional and organic fertilization. The results showed that coupling organic fertilizers and bioinocula, including diverse arbuscular mycorrhizae species, enhance raspberry growth and soil fertility. Thioredoxin VdTrx1 (an unconventionally secreted protein with biological functions inside and outside of the cells) in fungal tissues involves scavenging intracellular reactive oxygen species and sulfite assimilation. Tian et al. showed that Thioredoxin VdTrx1 is a virulence factor in Verticillium dahlia.
The results further confirmed that VdTrx1 is necessary for the full virulence of V. dahliae on susceptible hosts. Mangroveassociated microorganisms have received increasing attention due to their important ecological roles and the wide range of services they provide to the environment and economy. Zhu et al. used high throughput sequencing of the internal transcribed spacer 2 (ITS2) to assess epiphytic and endophytic phyllosphere fungal communities of six true mangrove species and five mangrove associates. The results of this study highlight the important role of plant phylogeny in the assembly of epiphytic but not endophytic fungal communities in mangrove ecosystems. To understand the resistance mechanisms of the Ganoderma lingzhi response to Trichoderma hengshanicum infection, Wang T. et al. observed G. lingzhi transcript accumulation at 0, 12, and 24 h after T. hengshanicum inoculation. The results revealed that the downregulation of differentially expressed genes led to the inhibition of heat shock protein (HSP) function, which compromises the HSP-mediated defense signaling transduction pathway, leading to the susceptibility of G. lingzhi. Miang, a traditional fermented food product produced from the leaves of Camellia sinensis var. assamica is found in the hill areas of Northern Thailand. Using the culture-dependent method, Kanpiengjai et al. investigated the yeast ecology of C. sinensis var. assamica tea flowers collected from six provinces in upper Northern Thailand. They characterized the tannin tolerance ability of the isolated yeasts. This study suggests that floral nectar supports the formation of yeast communities beneficial for Miang production. Paridis Rhizoma is a Chinese medicinal herb with strong anti-inflammatory and anti-tumor properties. Chen Y. et al. showed that the inhibitory effects of fermented Paridis Rhizoma extract (PRE) on liver cancer cells (Hepal-6), cervical cancer cells (Hela), and lung cancer cells (A549) are stronger than that of the unfermented extract. Venturia carpophila, the causal agent of peach (Prunus persica) scab disease, mume (Prunus mume), and apricot (Prunus armeniaca), is widely distributed around the world. Zhou et al. carried out the genetic variation and population structure in V. carpophila isolated from peach, mume, and apricot in China. They found that the genetic identity of V. carpophila isolates depends on the host, not the geographic region. Morphological characteristics and multigene phylogenetic analyses are used as the latest techniques for fungal species identification. Tennakoon et al. introduced Montagnula acaciae, Paraconiothyrium zingiberacearum, and Paraphaeosphaeria brachiariae, as distinct new species from dead plant litter based on morphological differences and DNA sequence data. In addition, Montagnula jonesii, Paraconiothyrium fuckelii, Spegazzinia deightonii, and S. tessarthra were reported as new host records from Ficus benjamina, Dimocarpus longan, Hedychium coronarium, and Acacia auriculiformis respectively, for the first time. Furthermore, Paraconiothyrium archidendri and P. brasiliense were reported for the first time from Magnolia sp. in China, and Paraconiothyrium rosae was synonymized under Pa. fuckelii. Introducing exotic or non-native trees fails due to a lack of suitable fungal partners. Wang R. et al. showed that exotic P. radiata is a suitable tree capable of successfully getting established by interaction with the co-introduced L. deliciosus or local ectomycorrhizal fungi. However, care should be taken when largescale planting of P. radiata is done. Plants of the genus Iris are widely cultivated because of their medicinal, ornamental, and economic values. However, it often suffers from Alternaria leaf spot or blight disease, leading to considerable losses for its commercial value. Gou et al. isolated 122 Alternaria strains in section Alternaria from diseased leaves of Iris spp. in 14 provinces or municipalities of China from 2014 to 2022. They introduced two novel and two known species that can induce leaf spots in Iris. In Sichuan province, Juglans regia, J. sigillata, and the hybrid J. regia × J. sigillata are the commercially important walnut plants, while J. regia is the most widespread walnut plant. In order to update fungi associated with Sichuan walnuts, Xu et al. surveyed 15 representative regions in Sichuan. The survey revealed 10 fungi belonging to Dothideomycetes and Sordariomycetes that were described based on morpho-molecular analyses. Rhododendron, an essential ornamental plant, is abundant in Yunnan Province of China, and 61 species of Rhododendron have been reported from Cangshan Mountain in Yunnan. Gu et al. introduced six new fungal species isolated from fresh leaves of Rhododendron cyanocarpum, R. decorum, and R. delavayi at Cangshan Mountain for the first time. Ganoderma is a globally distributed genus covering ecological, medicinal, economic, and cultural species. He et al. used morphology and multigene phylogeny to identify 21 specimens of Ganoderma collected in the Yunnan Province of China, representing 18 species. In addition, a checklist and a key to Ganoderma in Yunnan Province were given in the paper. Drought stress is one of the major abiotic factors that limit plant growth and cause ecological degradation. To investigate the role of arbuscular mycorrhizal fungi (AMF) on reactive oxygen species (ROS) generation and ROS scavenging ability under drought stress in Bombax ceiba, Li et al. carried out an experiment. The results revealed that AMF inoculation could maintain ROS homeostasis by mitigating drought-induced ROS burst via decreasing ROS generation and enhancing the ROS scavenging ability of B. ceiba seedlings.
Plant diseases caused by oomycetes inflict severe damage to various crops; however, biocontrol of oomycete-related diseases is poorly done. In this regard, Liu et al. used 86 Trichoderma isolates against Phytophthora nicotianae, Ph. capsici, Pythium vexans, Py. ultimum, and Py. dissotocum through dual culture assay and the results showed that the fungal strains exhibit strong antagonistic effects against oomycete pathogens, and those fungal strains can be integrated into disease management strategies. Multiple interactions happen between host plants and phyllosphere microbes, such as bacteria, oomycetes, and fungi. Wang K. et al. explored the interaction of Protomyces arabidopsidicola (isolated from phyllosphere), with Arabidopsis plant and found that Pr. arabidopsidicola strain C29 is pathogenic on Arabidopsis Author contributions SK drafted the editorial. All authors contributed to editorial revision and approved the final paper.

Funding
This work was supported by Yunnan Revitalization Talents Support Plan (Young Talents Program and High-End Foreign Experts Program).